Momentus 5400.6 & Scorpio Blue: Seagate & WD 2.5" HDDs at 500GB

Our samples were tested according to our standard
hard drive testing methodology. The significant change in our testing procedure is that as of mid-2008, we're conducting most acoustics tests in our own anechoic chamber, which results in more accurate, lower SPL readings than before, especially as the SPL approaches 20 dBA and below, which is the territory of laptop drives. Our methodology focuses specifically on
noise, and great effort is taken to ensure it is comprehensively measured
and described. Performance is not tested comprehensively, for reasons discussed in detail in
the methodology article. In essence, between similar drives, we feel the performance differences are trivial, while the noise differences can be significant. Furthermore, many other hardware review sites (such as The Tech Report, Anandtech, and X-bit Labs) do a good job of covering the performance (speed) aspects of HDDs, while none of them do a thorough job of noise analysis.

A. ACOUSTICS

Two forms of hard drive noise are measured:

Airborne acoustics

Vibration-induced noise.

These two types of noise impact the subjective
perception of hard drive noise differently depending on how and where the drive
is mounted.

Both forms of noise are evaluated objectively and
subjectively. Airborne acoustics are measured in our anechoic chamber using a lab reference
caliber microphone and computer measurement system. Measurements are taken at a distance of one meter from the top
of the drive using an A-weighted filter. Vibration noise is rated on a scale
of 1-10 by comparing against our standard reference drives.

A final caveat: As with most reviews, our comments
are relevant to the samples we tested. Your sample may not be identical. There
are always some sample variances, and manufacturers also make changes without
telling everyone.

The results of the acoustic and vibration tests were somewhat surprising. First, despite the Seagate's apparently lower acoustic spec, the WD was actually quieter at idle  by just under 1 dBA@1m. Subjectively, this difference is insignificant. What's more surprising is that the WD measured lower in airborne noise despite its much higher level of vibration. Our standard procedure of placing the tested drive on a soft foam pad helped keep the measured SPL of the WD low by isolating the vibration from being transferred to the workbench  the workbench top would have become an acoustic diaphragm for the drive.

The WD Scorpio's vibration level was high enough for possible shipping damage to be suspected, but S.M.A.R.T analysis using WD's own Lifeguard Diagnostics sofware indicated perfectly good health for all of the tracked criteria.

The frequency spectrum captures below shows that the WD measures 10 dB higher at the primary 90 Hz tone of the spin speed (5400RPM), which is indicative of the vibration difference between the drives. Also evident is a higher midband peak in the Seagate which is probably responsible for the slightly higher overall SPL.

In the WD, the difference in perceived noise between seek and idle was so small to be trivial under the test conditions. There was a touch more audible noise when listened at about 1' distance, but the measured SPL increase was less than 1 dBA@1m on average. Hitachi Tool gave access to AAM on the WD; there's no point enabling it because there is no perceptible difference between lowest acoustic and highest performance. The low noise position always increases the access time.

Seek noise in the Seagate was more marked. AAM is not supported on this drive, so HD Tach was used to engage seek. The chattering caused SPL to rise about 2 dBA@1m higher than at idle.

Both drives had very low power demand, with the Seagate a touch lower across the board. With both drives, the heads unloaded after less than ~10 seconds of inactivity, then power demand dropped another 0.1~0.2 W. The load figures of 2.2 W and 2.5W are peaks; average load power was probably at least 10% less.

B. PERFORMANCE

High transfer speed is expected with the high areal density of these drives, and both samples delivered the expected performance. There's little to separate the two. It's interesting to note that the ~70 MB/s read speed of these 5400RPM drive easily surpass the manufacturer's specification of performance 59.0 MB/s for the 160GB 7200RPM Seagate Momentus reviewed a little over a year ago.